Frugivoria por aves em um fragmento de floresta de restinga no Estado do Espirito Santo, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

This study was conducted at the Reserva da Foz do Comboios (19°46 S - 40°02 W), state of Espírito Santo, Brazil. The RFC is a restinga forest fragment surrounded by anthropic open landscape and grows on an extensive coastal sand plain of quaternary deposition (about 5,500 years old). Additional infromation was collected at nearby sites. Fleshy fruits are available for avian consumption at RFC year round with the greatest number of fruiting plants occurring in the middle of the dry season. Fifty-eight species of plant species produce fruits with confirmed or potential consumption by birds. From February 1993 to February 1994, 68 species of frugivore birds were detected at RFC and of these, 47 species were studied. Forty-four species were seen feeding on fruiting trees and the other three species had fruit remains in their droppings. Most were Passeriformes, which accounted for 97% of total fruit consumption. The taxa richest in species were Tyrannidae (13 species, 5% fruit consumption) and Thraupinae (12 species, 67% fruit consumption). There was a predominance of small, omnivorous species with low sensitivity to environmental changes, little habitat specificity and wide Neotropical distribution. This is consistent with the theory that the very recent sedimentary plain where RFC lies could have been colonized by opportunistic bird species coming from nearby tabuleiro forests. Six species (Cyanerpes cyaneus, Euphonia violacea, Dacnis cayana, Cacicus haemorrhous, Tangara mexicana and Coereba flaveola) accounted for 74% of ali fruit consumed. Consumption rate (4.9 events/hour) was higher in open areas outside the forest and in forest border, and between sunrise and 11:00 h. Consumption frequency appears to be lower at RFC than in other previously studied Neotropical localities. Birds collected fruit most frequently while perched (93 % of observations). In most cases, fruit was taken whole (60%). Partial removal of pulp was more frequently observed in Emberizidae and usually involved Cecropia sp. catkins and Clusia hilariana fruits. The material removed was handled prior to swallowing (83 % of observations), mostly by mandlbulation. Seed ingestion occurred in 71 % of observations. Non-ingestion was observed mostly in Emberizidae and Icteridae. Visits to fruiting plants were short, 90% lasted less than 3 minutes and feeding visits were 3.5 times longer than nonfeeding visits. Birds fed at ali vegetational levels. In taller forest, only 5% of the feeding observations occurred in the under story. The frequency of aggressive confrontations between birds of the same or of different species was low (0.38 per hour), perhaps due to the low visitation rates and to the low overlap of feeding preferences (fruit size, feeding time and feeding height) amongst the most important avian consumers. Only 11 species (16% of avian frugivores at RFC) seem to be potentially good seed dispersers of the plants studied and for some plant species it was not possible to determine an efficient seed disperser. Low availability of fruits, low rates of fruit removal and the failure to detect the dispersers of some plant species point to the somewhat inefficient role of birds in the seed dispersal at RFC. These factors could add to the difficult of disturbed restinga habitats recovering naturally. It was not possible to determine if these and other features of the bird-fruits relationship arose due to the human impact that led to the fragmentation and deterioration of RFC restinga or if they were already present in the original, undisturbed habitat

ASSUNTO(S)

restingas ave

ACESSO AO ARTIGO

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